Health Advisories Issued for National Parks

Today –

Advisory Levels Explained »

Whenever ozone or particulate matter concentrations exceed or are predicted to exceed health standards, National Park Service (NPS) staff post health advisories cautioning visitors of the potential health risks associated with exposures to elevated levels. Most air pollution in National Parks is created outside park boundaries. When air quality conditions reach unhealthy levels in parks, conditions in the surrounding areas are usually similar.

Ozone Advisories

The NPS issues ozone health advisories when ozone concentrations are predicted to or exceed the
National Ambient Air Quality Standard. The ozone health standard is based on an 8-hour average concentration set at 70 parts per billion (ppb). Due to rounding, EPA considers an exceedance of the 8-hour standard when the ozone concentration exceeds 75 ppb. Using the EPA
air quality index
, the NPS ozone health advisories are based on the levels shown below.
Health Effects of Ozone »

Fine Particulate Matter Advisories

Air quality in some parks may at times exceed the
National Ambient Air Quality Standard
for fine particulate matter (PM
2.5
), particles less than or equal to 2.5 micrometers (µm). The 24-hour public health standard set at 35 micrograms per cubic meter parts (µg/m
3
) is used as a basis for health advisories in the parks. Using the EPA
air quality index
, the NPS PM
2.5
health advisories are based on the levels shown below.
Health Effects of Particulate Matter »

Participating Parks

The NPS issues air quality health advisories at several national parks. These parks include: